Locating and tracking of mobile terminals has attracted a lot of attention during the last years. The development of location technologies has been motivated and fueled by both commercial and non-commercial reasons. Many of the present and future services provided in mobile networks require information about the current location of the mobile terminal, whereby the operators are given an opportunity to increase their revenues by offering these services. Obtaining a reliable estimate of the location of a mobile terminal is also important in terms of public safety, for example. It is highly desirable that certain authorities, such as emergency call centers, are able to locate the mobile terminal accurately. Therefore, different authorities have set requirements for the location determination of mobile terminals.
The need to allow new location-based services to be developed has also been attended to in the standardization work of the 3rd Generation Partnership Project (3 GPP) by defining a general location service (LCS) architecture. FIG. 1 illustrates the general arrangement of the Location Service feature as illustrated in the 3 GPP technical specification TS 23.271 V.6.1.0. As shown in the figure, the external LCS clients 100 access the system through the Gateway Mobile Location Center (GMLC) 101. Generally, the LCS client refers to a software and/or hardware entity that interacts with an LCS Server, which in turn offers LCS capabilities within the Public Land Mobile Network (PLMN) and/or at the service provider. The LCS client is thus a logical functional entity that requests the location information of one or more mobile stations 102. The LCS clients are divided into internal and external clients (from the point of view of the mobile network). An external LCS client may be an application residing in the Internet, for example. Below, an LCS client refers to an external client, if not otherwise stated. The LCS Server in turn is a functional entity comprising the functions needed in GSM or UMTS networks to support location services. The LCS server consists of components that may be distributed to one or more PLMNs and/or service providers. Many of the functions belonging to the LCS server functional group are allocated to the GMLC. An external LCS client thus sees the GMLC as the LCS server.
FIG. 1 illustrates the general arrangement including three types of GMLCs: a requesting GMLC (R-GMLC) 101a, a home GMLC (H-GMLC) 101b, and a visited GMLC (V-GMLC) 101c. The R-GMLC is the GMLC that interacts with the LCS client, the H-GMLC is the home GMLC of the subscriber using the mobile station to be located, and the V-GMLC is a GMLC in the visited network, i.e. the GMLC associated with the serving node of the mobile station to be located. It is to be noted here that the requesting GMLC can be the visited GMLC, which can be the home GMLC at the same time, if the mobile station is in the home network.
The R-GMLC and H-GMLC may request routing information from the Home Location Register (HLR) or from the HSS (Home Subscriber Server) 103. The H-GMLC is responsible for checking the privacy of the mobile station to be located. The privacy check may be performed in the H-GMLC itself or in the Privacy Profile Register (PPR) 104, which is accessible from the H-GMLC.
The R-GMLC receives service requests from the LCS clients. In this context, such a service request, which requests the location of a certain mobile station, is termed an LCS service request. An LCS service request received by a requesting GMLC is forwarded to the visited GMLC via the home GMLC. If the radio access network is the GSM EDGE Radio Access Network (GERAN) 107, the V-GMLC then forwards the request to the Mobile services Switching Centre (MSC) 105 or to the Serving GPRS Support Node (SGSN) 106. On the other hand, if the radio access network is the Universal mobile telecommunication system Terrestial Radio Access Network (UTRAN) 108, the visited GMLC forwards the request to the MCS server 109 or to the SGSN 110 associated with the radio access network.
The actual positioning method is then carried out in the radio access network and the response is returned to the GMLC, i.e. when the subscriber is roaming, the response is returned to the R-GMLC, via the V-GMLC and the H-GMLC.
A drawback relating to the above-described location service is that the SGSN and the MSC/MSC Server are not aware of pure WLAN terminals, i.e. terminals that access the services through the WLAN network only. Therefore, the location information cannot be provided with respect to these terminals.
The objective of the present invention is to eliminate the above-mentioned drawback.